Art of molding sheet metal



Feb. 17, 1931. B, CARNS 1,793,054

ART OF MOLDING SHEET METAL Filed April 9; 1927 2 Sheets-Sheet 1 Feb. 17, 1931.

E. B. cARNs 1 ,793,054

ART OF MOLDING SHEET METAL Filed April 9, 1927 2 Sheets-Sheet 2 V EZ T Z] Patented Feb. 17, 1931 UNITED STATES PATENT OFFICE EDMUND B. CAIRNS, OF NEW YORK, N. Y., ASSIGNOR T CAIRNS DEVELOPMENT CO]!!- IPANY, OF WILMINGTON, DELAWARE, A GOB-PORATION OF DELAWARE Application filed April 9,

My invention relates to improvements in the art of molding, pressing or shaping sheet metal. It often happens that it is desirable to shape sheet metal, especially for struts and the like, for use in aircraft, where the quantity consumed is not suflicient to warrant the expense of dies and presses. My invention is intended to meet this diiiioulty, generally, and to provide a method and means for economically producing shaped sheet metal structures. Generally, my improved means and method comprises forming a mold of refractory material having a form of the desired shape, placing the sheet metal 'over 5 this mold, and then depositing a mass of molten metal or other material having a high fusing point and sufficient weight upon the sheet, the molten metal being of a lower melting point than the sheet to be shaped and afterwards pressing, if necessary, the

molten metal upon the sheet, thus forcing the latter into the cavityof the mold and giving it the desired shape; or the molten metal can be forced against the sheet' in other ways if preferred. Obviously, it is necessary to provide means for confining the molten metal and for easy access to the mold. If the metal to be shaped is thin, the molten mass deposited on it may of itself be sufficient to depress and shape the sheet, and this is facilitated because the molten metal softens the sheet to be shaped and makes it very easy to press the sheet into the mold cavity. If, however, the weight of metal is not suflicient, my invention comprises means for adding an increment of pressure suflicient to press the softened sheet into its cavity. The formation of the sheet in this manner is easily accomplished and because of its softening it retains its shape readily and is not distorted when it issues from themold. In consonance with the above, I provide a mold of refractory material, over which a sheet can be placed, superpose a second mold member or metal retainer above the cavity mold", provide means for pouring molten metal into the upper member and also arrange a piston which can be used to give an added pressure when necessary to press the sheet into its cavity. It is also de 50 sirable to provide means for keeping both 1927. Serial No. 182,209.-

mold members and the piston hot during the process, so that the mold or the sheet to be formed willnot be chilled. After the sheet is formed the cavity is depressed somewhat and tipped over, thus dumping the molten metal and leaving the sheet in its desired shape; or the molten metal can be removed in any preferred way.

It will be understood from the foregoing that my idea might be carried out in many ways and in the accompanying drawings I have shown one way which is practical for accomplishing the foregoing result.

Reference is to be had to the accompanying drawings forming a part of this specification, in which similar reference characters indicate corresponding parts in all the views.

Fig. 1 is a longitudinal section through the apparatus suitable for carrying out my invention; Fig. 2 is a cross-section on the line 2-2 of Fig. 1; Fig. 3 is a cross-section of a modified form of apparatus for carrying out my invention; and Fig. 4 is a section of another slight modification.

The apparatus employs a suitable frame 10 of any approved design and in the lower part of'this frame I arrange a follower 11, which is movable up and down in the frame and can be moved in any suitable or preferred way. I have shown a quick and easy method of lowering and raising the follower, comprising a. series of toggles '12 which are pivoted to the follower and to the base of the frame and are actuated by a sliding rod 12'. This can be moved in any preferred manner. Above the follower and supported thereby, but separable therefrom, is a refractory mold 13, which has on the upper side a cavity 14 of the shape to which the metal sheet, hereinafter referred to, is to be pressed. This mold is preferably kept hot during the pressing or molding operation and any suitable means can be employed for heating it. I have shown it provided with chambers 15 which are heated by conventional gas burners 16 of the perforated pipe type, these being supplied with gas and air or combustion material through the flexible pipe 17, while a vent 15 is provided for each chamber. The mold 13 is provided with trunnions 18 at the ends, which project from the frame sides, and clearance 18' is provided for the neces sary slight vertical movement of the mold. The mold can be turned or tipped in any convenient way as, for example, by a crank handle 19 attached to one of the trunnions 18.

Above the mold 13 is a stationary mold member or container 20 chambered on the underside and fitting snugly upon the top surface of the mold 13. This has its chamber 21 adapted to be filled with molten material, and to assist in keeping the member 20 hot it is chambered as at 22 and provided with gas and air pipes 23 and 24:, which discharge into the chambers 22, the latter being provided with suitable vents. Any other suitable means for keeping the mold member hot can .be substituted. The mold member or container 20 has a vertical bore 25 through the middle part and around this is a guide collar 26 for guiding the vertically movable piston -27. This can be lifted above the collar 26 so that the molten metal may be poured through the collar to fill the container or mold member 20. It will be seen that the molten metal will act as a piston and that the mechanically actuated piston 27 is auxiliary and for the purpose of giving increased pressure and a quicker result. Like the other mold members of the apparatusthe piston 27 is chambered to act as a burner and provided with gas and air inlet pipes 28 and 28, while the exhaust is through the hollow shaft 29. This shaft is attached to and actuates the piston 27 which is guided in a collar 30 attached to a crossplate 31 in the frame 10. The shaft 29 can be actuated in any approved manner after the method of operating press dies or otherwise. The operation of the apparatus is as follows:

When the follower 11 is depressed the mold 13 drops sufliciently to permit a sheet 32 of material to be formed to be placed over the cavity 14. The follower 11 and mold 13 are then raised so as to bring the lower edge of the container mold member 20 into contact with the face of the mold 13, and firmly grip the edges of the sheet. The piston 27 will meanwhile be raised and a charge, for example, a crucible full of molten metal, is poured through the collar 26 into the container mold member 20, thus filling the contamer and lying upon the sheet 32. It will be seen that this mass of metal will immediately soften the sheet, and it will be understood that the metal charge should have a lower melting point than the sheet to be shaped. If the sheet is very thin, the weight of metal softening and pressing upon the sheet will press it into its cavity 14, but if the sheet has substantial thickness, additional pressure can be applied by means of the piston 27 and the softened and heated sheet quickly pressed to place. As all the mold members of the apparatus are heated, there is no danger of a chill and satisfactory shaping of the metal is had. After each operation the follower 11 is lowered and the metal charge dumped off the sheet 32 by tipping the mold 13 and this charge metal can be remelted for another charge.

From the foregoing desci'iption, it will be evident that so far as the apparatus is concerned it may be changed in many ways withoutaffecting the invention, for example, in Figure 3 I have shown the cavity mold 13 above the container mold 21 the cavity mold is moved up and down by a toggle arrangement 33 like that already described except that it is above instead of below the mold, and the metal sheet 32 is gripped between the two molds as already described. The molten metal in the container No. 21 is supplied from a well 34 which is heated as shown at 35. The piston 27 operates in a guide 36 and is connected with a hollow shaft 29. The piston is heated as already described. The molten metal can be introduced through the collar 36, and when the piston is depressed, it will force the molten metal against the sheet 32, thus pressing the sheet into its cavity and when the piston is raised,-the metal will fiow back from the container 21 into the well 34;. In Figure 1 I have shown another similar arrangement, but in this case the piston is dispensed with and fluid pressure through the shaft 29 or any preferred means can be used to move the molten metal.

It will be seen that my method and apparatus provide for the rapid and commercial shaping of sheets of metal, and that they disclose means for shaping sheets of large size; that the mold parts are quickly and easily separable, that if ithe sheet to be formed is not too heavy the mass of molten metal deposited upon it will serve to soften and shape the sheet without pressure, but that this pressure can be readily applied when needed. Care should be had, however, in using the molten metal of a lower melting point than that of the sheet to be shaped, or the latter will be destroyed. It will also be noted that the apparatus is eflicient because among other things means is provided in the form of a heater in close proximity to the molten metal for keeping the latter to the desired temperature and preventing a chill.

I have referred in this specification to molten metal as the material to be deposited upon the sheet to soften and depress it but it will be understood that other materials having sufficient weight and a sufiiciently high fusing point can be used if preferred without affecting the invention in any way.

I claim:

1. An apparatus of the kind described comprising a lower dumping cavity mold having means for heating it, an upper mold member in the form of a container for molten material fitting upon the cavity mold member, and means for heating the upper mold member.

2. An apparatus of the kind described comprising a cavity mold, a second member in the form of a container for molten material lying above and fitting upon the cavity mold with the open side of the container opposite the cavity mold whereby the weight of ma terial in the container tends to bend a'sheet of metal lying between the two mold parts, and a piston movable in and out with relation to the container member.

3. An apparatus of the kind described comprising a cavity mold, a second mold member in the form of a container for molten ma relation to the container member of the mold.

4. An apparatus of the kind described comprising a cavity mold, a vertically movable follower supporting the cavity mold, and a second mold member in the form of a container of material above the cavity mold and fitting the mold outside the edges of the cavity.

5. An apparatus of the kind described comprising a vertically movable follower or support, a dumping cavity mold above and supported by the follower, the follower and mold being movable also with relation to each other, and a mold member in the form of a container for molten material above the cavity mold, and fitting the face of the cavity mold outside the edges of the cavity.

6. An apparatus of the kind described comprising a lower cavity mold, a second mold member in the form of a container above and co-acting with the cavity mold, means for introducing molten material into the container, and means located in the apparatus and in close proximity to the molten material for heating the latter.

7. An apparatus of the kind described comprising a lower cavity mold, a second mold in the form of a container above and co-acting with the cavity mold, means for introducing molten material in the container, and means in the walls of the container for heating it.

8. An apparatus of the kind described comprising a lower cavity mold, a second mold member in the form of a container above and co-acting with the cavity mold, means for introducing molten material into the container, and means in the walls of the container and cavity mold for heating them.

9. An apparatus of the kind described comprising a lower cavity mold, a second mold member in the form of a container located above and co-acting with the cavity mold, means for quickly moving the mold members with relation to each other, a piston moving in and out with relation to the cavity mold, and a heater in the piston.

10. An apparatus of the kind described. 1 comprising a lower cavity mold, and a sec- March, 1927.

EDMUND B. CARNS. 

